The human cytomegaloviruses (CMV) are ubiquitous in human populations and are associated with numerous diseases. We are presently studying the molecular biology of human CMV infections including the molecular organization of the human CMV genome, the interaction of CMV with cells during permissive and nonpermissive infections, and the oncogenic transformation of cells by CMV. Our studies are focusing on the nature and association of the viral DNA with the cellular genome and on the regulation and characteristics of virus-specific transcription and translation products. A major limiting factor in these studies has been the difficulty of preparing reasonable quantities of pure viral DNA for use as a molecular hybridization reagent. In order to provide large quantities of well-characterized subgenomic fragments of the human CMV DNA genome, we are cloning Eco R1 restriction fragments of human CMV strain AD169 using the vector PACYC 184 in E. coli K12. The major objectives of our research are 1) to define thoroughly the molecular biology of human CMV infections in permissive cells, 2) to characterize the molecular events occurring during nonpermissive infections and their relationship to possible mechanisms of latency, and 3) to determine the oncogenic potential of human CMV.